Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

I traveled between 7500 and 10500’ today in the Lee vining area. I traveled on several aspects and dug in multiple spots to try and get a good idea of how things are feeling out there.

• Impressive surface oar growth has occurred BTL. Grains as large as 10mm were observed near the bottom of V bowl. Smaller grains were observed up to 9k in sheltered treed areas.
• The Wind outperformed the forecast today and decent flagging was observed along the Dana plateau and off the summit of East peak.
• With periodic probing I was able to identify the Presence of less cohesive facets at the base of the snowpack throughout most of my tour today. The exception to that is in areas NTL and ATL that have seen significant wind affects and are largely stripped.
• Solar aspects are starting to see signs of surface melt. MF crusts / melt forms were observed as high as 9500’
• I dug in at two locations. At 9800 on a NW aspect and at 10300’ on a NE aspect. I found a very similar structure in both locations. Take a look at the pit profiles for more details. In summary, the structure is still poor, and our basal facets are still producing Sudden Collapse fracture character and propagating test results in this area. The slab has gained strength and more force is required to initiate failure then I would have expected a week ago.
• Surfaces have been faceting and are largely loose and unconsolidated. In exposed areas near and above treeline in the east peak area surface conditions would be best described as wind pressed pow. Most areas contain a thin zipper crust, but I did observe a few favorable terrain features with more sizable wind deposits. I didn’t see any windslabs of concerning size, but I was able to sniff out a few sheets of wind board about ~4~ inch’s thick or so. I would not have been surprised if there had been more concerning deposits along ridgelines in the area today.